Scientific Forecaster Discussion

Aviation... 18z taf cycle abundant moisture associated from placement of the upper high over southern portions of the state will continue to fuel afternoon scattered to numerous rain showers and thunderstorms and rain across western and central New Mexico. Convective coverage will peak from 18z to 00z. Storm motion will be mainly west to east...but slow moving and erratic at times. Look for brief periods of MVFR/IFR ceilings/occasional mountain obscured for sites impacted by strong to possible severe storms...following heavy rain and gusty winds near 40kt from outflow boundaries.

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Previous discussion...326 am MDT sun Aug 2 2015... synopsis... today will be yet another day of very high atmospheric moisture content across New Mexico...and as temperatures rise the atmosphere will become unstable with periodic redevelopment of scattered to numerous showers and thunderstorms. Many storms will be capable of producing locally heavy rainfall again with a continued threat for flash flooding in localized areas. Finally...into Monday drier air will begin filtering into New Mexico from the west...shunting the best probabilities for precipitation to the east with much less overall storm activity. This drier period is expected to last through the middle part of next week with fewer storms and warmer temperatures.

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Discussion...

While yesterday's abq balloon sounding revealed a slight reduction in precipitable water at 1.03 inch...analyzing radar storm totals indicates that the footprint of rainfall yesterday and last evening was still fairly widespread over much of the forecast area with hefty totals of one to two inches being common. Forecast models show the precipitable waters remaining above average today...and the NAM actually reveals some impressive values of 1.3 to 1.5 this afternoon over many central zones...including the Albuquerque metropolitan area. This coupled with the antecedent wet conditions and saturated soils has prompted the issuance of yet another Flash Flood Watch for a large chunk of the forecast area...roughly the northwestern half or so. Other synoptic features of note will be the consolidation of the upper high over southern nm and a speed maxima working into western parts of the state where 300 mb winds are projected to reach almost 40 knots. This speed maximum could vent storm updrafts...making them a bit more efficient while also introducing some divergence aloft that would enhance synoptic scale upward motions. Storms should propagate from the SW to NE or west to east for the most part...except in the north central to northeastern zones where motions will be a bit more erratic and slow. Otherwise temperatures will be fairly seasonable...running just a few degrees below average in the western zones.

Into Monday the pronounced dry slot aloft that is currently working inland off of the eastern Pacific will be spreading east toward nm. This will quickly lower dewpoints and precipitable waters in the western zones Monday...limiting storm potential substantially from the trends of the past several days. Still some isolated to scattered storms will be possible...but should be more focused toward the Central Mountain chain and to a lesser extent the eastern plains of nm.

The drying trend continues into Tuesday...and storm coverage will continue to dwindle as the dry air filters into remaining eastern zones of the forecast area. Probability of precipitation have been ratcheted down over the past few shifts...and some minor tweaks down were also carried out for this current forecast package. With the drier air filtering in...temperatures will observe larger diurnal swings...first in the west Monday and Monday night...then into remaining zones Tuesday.

By the middle of the week the drier air will still be in place while the dome of high pressure centers up squarely over nm with heights rising to the 594-595 decameter range. This will suppress convection...but some isolated storms will still be able to fire over high terrain areas. High temperatures will creep up a few degrees too.

Into Friday an upper trough will move off of the Pacific into California. This feature has been shown to be somewhat disconnected from the polar jet the past few model runs...keeping a slower and farther south track. This would be favorable for shoving the dome of high pressure east of nm while drawing subtropical moisture northward from the Sierra Madre Occidental and ultimately increasing thunderstorm activity into the weekend.

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Fire weather...

Based on water vapor imagery...upper high center located over south central New Mexico early this morning...with abundant moisture lingering over the region. Cell motion today should be mainly towards the east...although some slow and erratic motion possible. Potential for locally heavy rainfall again today...especially northern and western two thirds of the state.

Models continue to insist on a drier and warmer trend...and are even more bullish with lower dew points spreading across the west and north Monday and Tuesday. Did not totally buy into the degree of drying projected on Monday...given the deep moisture currently over the far west...but Tuesday seems more reasonable to trend more toward the model forecast. Water vapor imagery does indicate drier air to our southwest...but several disturbances and less dry air queued up west of California. The disturbances are currently forecast to ride over the ridge and to our north...but the size of the dry slot appears to be shrinking a bit at this time so will continue to monitor. If current model trends persist...only isolated convection anticipated for the west Monday...and for most of the forecast area Tuesday through Wednesday. With the drier air will come highs near to above average and a forecast of high Haines. Winds should remain relatively light though with min relative humidity values mostly above 15 percent and good overnight recoveries.

Return of monsoon moisture still on tap for late this week and through the weekend. Drier westerlies could resume early next week...with the GFS suggesting a stronger trough passing through the northern rockies than the European model (ecmwf).

Some areas of fair to poor vent rates north and east today and Monday with improvement overall Tuesday and Wednesday forecast.

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Abq watches/warnings/advisories... Flash Flood Watch through this evening for the following zones... nmz501>519-521>523-527>529-532-533.